Telephone-exchange system



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Filed Dec'. 20, 1919' 2 Sheets-Sheet 2 w Ge/o N www AIJI SN. '.FIJUH @ilvllQN mai @EN \N NVN Ir w8;

Patented Aug. 21, 1923.

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STATES FATNT @DFFHCEQ GEORGE .ALBEN E. LUNDELL, OF CHICAGO, ILLINOIS,ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y.,A CORPORATION OI? NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application led December 20, 1919. Serial No. 346,351.

To all 'whom it may concer/a:

Be it known that I, GEORGE ALBEN E. LUNDELL, a citizen of the UnitedStates, residing at Chicago, in the county of Cook and State ofIllinois, have invented certain new and useful Improvements inTelephone- Exchange Systems, of which the following is a specification.

This invention relates to automatic telephone exchanges, and moreparticularl to full automatic telephone exchanges in w ich senders areemployed for registering .the numerical designation of the called lineand for controlling the setting up of the connection.

In such automatic exchanges registers are set into position by themanipulation by the calling subscriber of a calling device or dial. Theoperative circuit of such calling device includes the line wiresconnectinv the substation with the central office, andD a control relayand source of energy at the central oiice, and over this circuitimpulses of curl rent are transmitted.

The correct operation of the central oflice selecting mechanism dependsupon the proper operation o-f this circuit. Hitherto, it has been foundthat when the calling subscriber is one of the parties on a poly-stationline, that is a line having a plurality of substations and having only asingle pair of wires extending from such stations to the central oflice,the operation of the pulse circuit is rendered unreliable by theshunting` effects of the condensers at the other stations of the line.

It is the object of the present invention to provide a simple andefficient pulse circuit for such poly-station lines, whereby theaccuracy and reliability of the registering operation is improved.

Another object of the present invention provides for the use of a slowrelease relay for controlling the shifting operation whereby oneregister after the other may be rendered active in connection with thepulse circuit. According to this feature a contact of such slow relay incombination with the register switches, initiates the Sending operationand controls the restoration of the register switches. A simple form ofregister control switch is thereby obtained.

A further object relates to an improved selection of the ringing currentfor polystation lines, whereby a single set' Of terminals may be usedfor all of the stations of the selected line, onl one set of impulsesbeing required for se ection of both the line and the ringing current.

It is understood that the disclosure herein 'set forth is only one of avariety of expressions which the invention is capable of receiving, andthat the scope of the invention is not to be determined by it, referencebeing had to the appended claims for that purpose. The invention will beunderstood more in detail by reference to the accompanyin drawings,wherein is disclosed so much of a telephone system as is necessary to a,full understanding of the invention. Figs. 1 and 2 taken collectivelyrepresent a connection from a calling to a called subscriber. Fig. 1represents a first selector and control apparatus therefor, a senderincluding the counting relays, a plurality of register switches, aregister control switch and controlling relays therefor; and shows apartyline having four stations. Fig. 2, which is to be placedimmediately to the right of Fig.` 1 represents a. second switch of thetrain, extending from a callin subscriber to a called. subscriber, andinclu es selective ringing apparatus for signalling the individualstations of a poly station line. Fig. 2 also includes a portion of thecounting relays of the sender 119.

In Fig. 1 the subscribers station 101 comprises the calling device 102,the purpose of which is to produce operating impulses by interruptingthe circuit at the substation. Stations 100, 101, 103, 104, areseverally connected to the line wires 105, 106. Such stations areprovided with ringers 107, 108, 110, and 111, each of whichl is normallyin series with a condenser such as 112.

The conductors 105, 106 of the calling line may be extended to the firstselector by means of a line finder or equivalent, upon the removal ofthe receiver at the calling station. Such first selector may be of anysuitable type, that shown in the drawings being a so-called panelselector in which the terminals are arranged in vertical rows, and inwhich the wipers are adapted to travel in a vertical direction. Sequenceswitches 131, 154, and 213 comprise sets of springs such as that shownat 191, adapted to close contacts in the various positions of thesequence switch. r1he numerals which appear adjacent to the sequenceswitch conthe sequence switch tacts diagrammatically represented invarious parts of the drawings, indicate the positions of the sequenceswitch at which these contacts are closed, with the exception that thecentering springs, one of which appears immediately above the powermagnet of each of the sequence switches, are open only at the positionsindicated by the numeral adjacent thereto, and therefore the sequenceswitches can stop only in these positions. Motor mechanism is providedforv rotating the sequence switch through its successive positions. Thismechanism is set into operation during the energization of the powermagnet in the sequence switch.

Sequence switch contacts 125 and 124 of the sequence switch 131,associated with the first selector switch, 'are adapted in position 1 ofthis sequence switch to extend conductors 106 and 105 to conductors 123and 126, which in turn may be extended to the sender circuit 119 bymeans of a line finder, or equivalent means. The sender includes 154,the counting relays designated 0, 0', 1, 1, etc., as well as a pluralityof register switches, and a register control switch therefor. In thesystem of the present disclosure two register switches are shown, thefirst-controlled by the magnet 138, which upon energization of itsmagnet and attraction of its left hand armature causes the pawl 140 tostep the ratchetV wheel 141 and the wipers 120, 130, 142, and 143, in aclockwise direction. The ratchet wheel 141 and the wipers 120, 130,

142, and 143, are thus stepped in a step by step movement -one stepforeach .movement of the pawl 140. The retraction of the armature ofmagnet 138 withdraws the pawl 140 from a tooth of the ratchet wheel 141and places it in position for again adthe ratchet wheel 141 upon subse.

vancing quent operation of the magnet 138. Similarly magnet 148 controlsthe movement of the ratchet wheel 151 and the wipers 122, 127, 152, and153, said magnet, ratchet wheel, and wipers being parts of the secondregister switch adapted to register the second digit of the numericaldesignation of the called subscribers number. The register controlswitch comprisesthe stepping magnet 144 with its ratchet wheel 146 andthe wipers 145 and 136. vThe energization of the magnet 144 attracts thearmature 91 .and moves the pawl 92 into engagement with l the next toothof ratchet wheel 146. Upon deenergization of magnet 144 and theretraction of armature 191 pawl 192 forcesthe'ratchet wheel 146 and thewipers 136 and 145 one step in a counter clockwise direction. Each ofthe wipers 120, 130, 142, 143, 122, 127, 152, 153, 136, and 145 isprovided with a row of terminals with which it makes contact and uponbeing stepped away from the last terminal of the row is .calledsubscribers number.

brought again into engagement with the first or normal terminal.Selector 220'of Fig. 2 is of the so-called panel typ and is providedwith wipers 223, 224, an 225,

adapted to move in an upper direction over the terminal bank 226, andwith commutator brush 214 which passes over the conducting Segments suchas 215, 228, and 231, of the coinmutator plate 227. A source of ringingcurrent 232 produces a plurality of variously characterized currents andthe ringers 107, 108, 110, and 111 of the call- YSuch central office.When the subscriber at station 101 desires to originate a call for asubscriber such as 201, he removes his re- .ceiver from the switch hook.A circuit is closed from grounded battery 117, pulse relay 118, registerswitch wiper 120, conductor 123, sequence switch contact 124, conductor106, substation equipment 101; interrupter 102, conductor 105, sequenceswitch contact 125, conductor 126, register switch wiper ,127, conductor128, register switch wiper 130 to ground. The op/eration of relay 118closes a loycal circuit from grounded battery 132,

winding of slow release relay 133, conductor 134, front contact of'relay 118-,to ground, operating the relay 133.

The subscriber at station 101 now manipulates the calling device orinterrupter 102 in accordance with the first digit of the For thepurpose of illustrating we will assume that the calling deviceinterrupts the circuit three times.

Th'e release of relay 118 upon the first opening of interrupter 102,causes the closure of the following circuit, ground, armavture and backcontact of relay 118, front contact of relay 133, windingof rela-y 135,register control switch wiper 136, conductor 137, register switch magnet138 to grounded battery. The energization of magnet 138 attracts itsarma-ture which by means of the pawl 140 causes the movement of theratchet wheel 141 and the wipers 120, 130, 142, 143, one step in aclockwise direction. The opening of the contact- 102 has left a chargefrom the battery 117 on the condensers 113,114, 115. The movement of thewipers 120, 130, from the first point to the second point of their arcscauses a flow of current from grounded battery register switch wiper122, conductorv accesso 117 through winding of relay 118 to theconductor 128 in turn throuvh wiper 127, conductor 126, sequence switccontact 125 to the conductor 105, thus to the side of the condensers113, 114, 115, opposite that to which this groundedbattery waspreviously connected. Similarly the ground connection by way of wiper130 is shifted to the conductor 121, wiper 122, conductor 123, sequenceswitch contact 124, conductor 106 to the side of the condensers 113,114, 115, opposite to that to which this ground was previouslyconnected. Thus it will be seen that a source of current flows throughthe winding of relay 118, as a result of the prev ious charge left onthe condensers 113, 114, 115, being discharged through-the pathdescribed, and furthermore as a result of a new charge in the oppositedirection to such condensers. Contact 102 of the calling device nowcloses and reestablishes a circuit for relay 118 as follows: groundedbattery 117, winding of relay 118, wiper 120, conductor 128, wiper 127,conductor 126, sequence switch contact 125, conductor 105, interruptercontact 102, substation equipment 101, conductor 106, sequence switchcontact 124, conductor 123, wiper 132, conductor 121, wiper 130 toground. The operation of relay 118 has been materially assisted andquickened by the surge of current through, the oondensers. A secondopening of interrupter contact 102 again deenergizes the relay 118 andcauses the operation of magnet 138 a second time. The consequentoperation of the magnet 138 again moves the ratchet wheel 141 and thewipers 120, 130, 142, and 143, to the third point, and a connection isthus 'established from grounded battery 117 over which the condensers113, 114, 115, discharge through the relay 118, and take up a new chargein the opposite direction, so that the surge of current through thewinding of relay 118 assists the operation of this relay as previouslydescribed. Thus it will be seen that the operation of the registermagnet 138 and the movement of wiper arms 120 and 130 alternatelycharges and discharges the condensers 113, 114, and 115, the charge anddischarge path including windings of the relay 118 and consequentlyaiding `the operation of this relay. Upon each release of the armatureof the relay 118 a circuit is closed through the winding of slow releaserelay 135 as described above. r1`he relay 135 is slow acting and remainsenergized'during the vibration of the armature of relay 118. Relay 135closes also a circuit for magnet 144 from ground, armature and frontContact of relay 135, winding of magnet 144 to grounded battery 117.Magnet 144 vcontrols upon its deenergization the stepping of theregister control switch ratchet 1,46 and wipers 136 and 145,

After the mlling subscriber sends out the first series of impulses thecontact 102 remains closed, and the relay 118 remains operated, for asuciently long period to allow the deenergization of slow acting relay135, wh-ich in turn opens the circuit ot the magnet 144. Thedeenergization of' magnet 144 results in the movement of ratchet Wheel146 and wipers 136 and 145 one step in a counter clockwise direction.

The calling subscriber now proceeds to send out the second set ofoperative impulses causing the intermittent operation of the relay 118for each opening of the interrupter contact 102, relay 118 releases onceand closes once the following circuit: grounded battery 147, secondregister switch magnet 148, conductor 150, register control switch wi er136, now in its second position, win ing of slow release relay 135,front contact of relay 133, back contact and armature of relay 118 toground. Register switch ratchet wheel 151 and its wipers 122, 127, 152,and 153, are thus caused to step one step in a clockwise direction foreac-h o ning of contact 102. Wipers 122 and 12 register switch reversesthe connections to the line wires 105, 106, in a manner similar towipers 120 and 130 of the first register switch, and causes, aspreviously described, a discharging and charging surge for the relay 118in the above described manner; and 'upon the cessation of the second setof impulses slow relay 135 is released, and magnet 144 is deenergized,thus moving the ratchet wheel 146 and the wipers 136 and 145 one step ina counter clockwise direction.

As soon as the first set of impulses was sent in and the slow releaserelay 135 was deenergized, a starting circuit for initiating themovement of the sender sequence switch 154 is closed from groundedbattery, 'power magnet of sequence switch 154, upper contact of sequenceswitch spring 155, conductor 156, wiper 153, conductor 157, wiper 143,conductor 158,back contact of relay 135 to ground, and under control ofcentering cam 160 sequence switch 154 is moved from its first t0 itssecond position. The sender sequence switch 154 now controls theselecting. operation in the following manner. Upon reaching position 2the sequence .switch contact 161 closes the following circuit:- groundedbattery, winding of relay 162, lower right contact of sequence switchspring 163, conductor 164, winding of stepping relay 165, sequenceswitch contact 161, left hand back contact of the 0 counting relay,conductor 166, lower contact of sequence switch spring 167 to ground,energizing relays 162 and 165. Relay 162 closes at its left. hand frontcontact by way of conductor 168, and lower left contact of sequenceswitch spring 163, a locking circuit during such movement of second" foritself independent of the lower ri ht contact of sequence switch spring163. he operation of relay 162 also closes a driving circuit forsequence switch 131, said circuit including the power magnet l sequenceswitch 131, upper left contact of sequence switch 170, right hand frontcontact of relay 162, to ground, causing the movement of sequence switch131 out of position 1 into position 2. When sequence switch 131 leavesposition 1, the orivinal circuit of relay 162 is opened at the Towerright contact of sequence switch spring 163, but this relay ismaintained energized over the looking circuit described.

The operation of relay 165 in the circuit described above causes thenumber 3 counting relay to be operated in the following circuit:grounded attery, winding of counting relay 3, back contact and armatureof counting relay 3', conductor 3, wiper 142, which is in its fourthposition, lower contact of sequence switch spring 171, front contact andarmature of relay 165 to ground. Count-'ing relay 3 becomes energizedand closes for itself the locking circuit by way of sequence switchcontact 172, armature and front contact of counting relay 3, winding ofcounting relay 3', winding of count-- ing relay 3 to grounded battery,independent of the previously described circuit through the wiper 142,and the contact of relay 165. lthough the winding of counting relay 3 isincluded in such locking circuit, this relay does not become energizeddue to a short circuit around said winding by way of wiper 142, and thecontact of relay 165. A circuit is now closed from a rounded batterythrough the winding of a riving magnet 173, sequence switch contact 174,right Afront contact of relay 162 to l ground. The magnet 173 byattracting its armature 175 forces a brush rod 176 against a roller 177constantly driven in the direction indicated by thev arrow. Under thecontrol of this roller the brush rod 176 and with wipers 178, 180, and181, and the commutator brush 182 mounted thereon is moved in an upwarddirection. Wipers 178, 180 and 181 are adapted to wipe over the contactsof terminal bank 183, and brush 182 is adapted to travel over theconducting and insulate-d segments 184 and 185 of a commutator plate186.

When brush 182 reaches the first conducting plate 184 it connects groundthrough a conductor 187 and the upperl contact of sequence switch spring163, causing thus the short circuiting of stepping relay 165. Upon itsdeenergization Stepp-'g1g relay 165 removes the short circuit m aroundthe winding of counting relay 3', and this relay becomes energized.Counting relay 3 connects the conductor 3 through its armature, andfront contact, and. the ermovin mature and back contact of countingrelay 2 to counting relay 2, which then operates in the Samemanner ascounting relay 3, to close a locking circuit for itself, and for thecounting relay 2.', when brush 182 reaches the next conducting se ent184. Thus when -said brush, 182 reac es the insulated segment 185, theshort circuit is removed from the stepping relay 165, and this relaypermits the operation of counting relay 2. The operation of the countingrelays continues in the same manner as descrlbed in connection withcounting relays 2 and 3, until the counting relay 0 becomes energized.This circuit opens at its left hand armature, and back contact, thecircuit of relay 165, thus preventing the reenergization of steppingrelay 165. The circuit of relay 162 is opened when brush 182 encountersthe next insulating segment.

Relay 162 closes a circuit from grounded battery power magnet vofsequence switch 131, lower left contact of sequence switch spring 170,rifrht hand back contact and armature of relay 162 to ground, and formoving sequence switch 131 under control of centering spring 188 intoits eighth position. The release of relay 162 opens the circuit of thedriving magnet 173, causing the stopping of wipers 178, 180, and 181, inengagement with trunk conductors 202, 203, and 204. The testing of thistrunk is accomplished in a well'known manner in position 6 of theAsequence switch 131, a circuit being closed from grounded batterythrough wlnding of the relay 205 of Fig. 2, test conductor 204, wiper181, and sequence switch contact 190 to ground. Relay 205 becomesenergized. The opera-tion of the counting f relay closes a circuit fromgrounded battery power magnet of sequence switch 154, upper contact ofsequence switch spring 191, inner armature and front contact ofcountswitch 154 under control of its centering cam 160, out of position2 and into position 3. l

The release of the slow acting relay 135 after the second set ofimpulses has been transmitted, closes the following circuit: ground,armature and back contact of relay 135, conductor 158, wiper 143, whichis in an off normal osition, conductor 157, wiper 153, which is 1n anolf normal position, conductor 193, upper contact of sequence switchspring 194, power magnet of sequence switch 154 to grounded battery, for

sequence switch 154 under the control o centering cam 160 out ofposition 3 and into position 4. During the movement of sequence switch154 from position ing relay 0 to ground, for moving sequence ,moves into16.

` A circuit is vnow closed from grounded battery 206 of F ig. 2, Windingof relay 207, lower left Contact of sequence switch spring 208,conductor 202, wiper 178, lower contact of sequence switch spring 195,conductor 164, stepping relay I165, sequence switch contact 161, lefthand back contact of the 0 vcounting relay, conductor 166, lower contactof sequence switch spring 196, wiper 180 conductor 203, lower c'ontactof sequence switch spring 210 to ground, operating relays 207 and 165.Relay 207 becomes energized and closes at its right hand front contact acircuit by way of conducto-r 211, and lower right contact of sequenceswitch spring 208, a locking circuit for itself independent of lowerleft contact of sequence switch spring 208. The operation of relay 165in the circuit described above, causes the operation of the countingrelay to whose conductor wiper 152 has been connected by the operationof the second register switch in the same manner as described for thenumber 3 counting relay above. It will readily be understood that Athewiper 152 and the counting relay conductor to which it is now connectedhas been determined by the number of impulsos transmit-ted to registermagnet 148, which number in turn is dependent upon the designation ofthe called stat-ion. For the purpose of the present description it maybe assumed that wiper 152 has been stepped three steps, and has beenconnected to con ductor number 3.

The opera-tion of relay 207 has closed at its left hand front contact acircuit by way of lower left contactof sequence switch spring 212 forthe power magnet of sequence switch 213, causing the movement of thissequence switch out of its first position. As soon as sequence switch213 moves out of its first position the lower left contact of sequenceswitch spring 208 is broken, but relay 207 is maintained energizedindependent thereof. As soon as sequence switch 213 reaches position 21a short circuit from ground is closed through the upper right contact ofsequence switch spring 208, whereby the stepping relay 165 isdeenergized and the counting relay of the upper row is operated. Themovement of sequence switch 213 under control of relay .207 continuesuntil the upper right contact of sequence switch 208 has short circuitedthe stepping relay 165 a suiicient number of times to operate the 0counting relay, whereupon relays 207 and 165 become released.

The operation of the 0 counting relay closes a circuit by way ofsequence switch spring 191 for moving sequence switch 154 out ofposition 4, and under control ofthe centering spring 160, this sequenceswitch The opening of sequence switch contact 172 releases the operatedcounting relays. In position 16 of sequence switch 154 a circuit isclosed from ground, armature and back contact of relay 135, conductor158, wiper 143, which is in an off normal position, conductor 157, wiper153, which is in an olf normal position, conductor 193, lower contact ofsequence switch spring 194, back contact and winding of the secondregister switch magnet 148, to grounded battery. Under control of itsback contact the magnet 148 is intermittently operated until the wipersare restored to the normal or first terminal whereupon the circuitthrough conductor 193 is broken, and the magnet 148 is deenergized. Acircuit is then closed from ground, armature and back contact of therelay 135, conductor 158, wiper 143, which is in an 0H' normal position,conductor 157, Wiper 153, conductor 156, lower contact of sequenceswitch spring 155, back contact and winding of register switch magnet138 to grounded battery, and under control of its back contact theregister switch magnet 138 is intermittently operated until wipers 120,130, 142, and 143, are returned to normal whereupon the circuit by wayof conductor 157 is broken, and the magnet 138 is deenergized. A circuitis now established from ground, armature and back Contact of relay 135,conductor 158, wiper 143, conductor 197, wiper 145, which is in an olinormal position, back contact and winding of register control switchmagnet 144 to grounded battery 117. Under control of its back contactmagnet 144 is intermittently operated, until the wipers 136 and 145 arereturned to their normal or first position, whereupon the magnet 144 isdeenergized.

A circuit is now closed from ground, armature and back contact of relay135, conductor 158, wiper 143, conductor 197, wiper 145, lower contactof sequence switch spring 191, power magnet of sequence switch 154 togrounded battery, for moving sequence switch 154 out of position 16.Under control of its centering spring 160 sequence switch 154 moves intoits -first or normal position. rlhe apparatus of sender 117, includingthe register control switch, the register, the counting relays, and thesequence switch 154 is now restored to normal and ready for use on asubsequent call.

When the sequence switch 154 reaches position 10, a circuit is closedfrom ground, sequence switch-spring 198, lower right contact of sequenceswitch spring 170, power magnet of sequence switch 131 to groundedbattery, for moving sequence switch 131 out of position 8. Under controlof its centering spring 188 sequence switch 131 moves into its 16thposition. Sequence switch springs 124 I local relay 133. A circuit isnow established from grounded battery 12, lower left winding ofrepeating coil 13, winding of relay 14, upper contact of sequence switchspring 124, conductor 106, substation 101, interrupter contact 102,conductor 105, upper contact of sequence switch spring 125, upper leftwinding of repeating coil 13 to ground. .Relay 14 is operated for apurpose which will subsequently be set forth.

Returning now to relay 207, which in the case consideredA releasedlafter sequence switch spring 208 applied the short circuit ground fourtimes, since it required four such closures to operate the 0 countingrelay, consequently relay 207 is Areleased when the sequence switch 213reaches positiony 6. A circuit is then vclosed from ground, brush 214,conducting segment 215, upper contact of sequence switch spring 216,conductor 217, driving magnet 218 of selector 220, to grounded battery.The magnet 218 by attracting its armature forces a brush rod 221 againstconstantly driven roller 222 and the brush rod 221 with Wipers 223, 224,

225, are moved in an upward direction over the contacts of terminal bank226, and brush 214 is moved in an upward direction 'over the commutatorplate 2 27. When brush 214 reaches conducting segment 228 a circuit isclosed Jfrom ground, brush 214, segment 228, lower contact of sequenceswitch spring 230, conductor 217, driving magnet 218, to groundedbattery, and the movement of brush rod 221 is continued. lSimilarly whenthe brush 214 contacts with such segments as 231 of the conductor plate227, the circuit of driving magnet 218 is maintained. When the brush 214passesoff segment 232 and makes contact with segment 233 the drivingmagnet 218 is deenergized, and the Wipers 223, 224, and 225 are stoppedin con-y tact with the terminals connected with conductors 255, 254, and248.` In shunt with the driving magnet 218 there is provided the relay238 which remains energized during the period of energization of drivingmagnet 218 and upon its release a circuit is closed from ground, uppercont-act of se# quence switch spring' 240, leftphand back contact ofrelay 238, conductor 241,.right hand armature and back contact of relay242, left hand back contact and armature of relay 243, conductor 244,winding of relay 245 to grounded battery 246, operating relay 245. Thebusy test is made in the usual manner. A ground is then applied by wayof the right hand armature and back contact of relay 238, sequenceswitch spring 247 to the Wiper 225, and totest terminal 248 forisolating the selected line. A circutis also closed from ground, lefthand armatureand back contact of relay 207, sequence switch spring 240,left hand armature and back contact of relay 238, conductor 241, arma-`winding of relay 242, left front contact of relay 245, wiper 224,conductor 254 the selective ringing apparatus of the called line,conductor 255, wiper 223, right armature and front contact of relay 245.Relay 242 is marginal and does not operate on the cur rent iowing inthis circuit. The ringer 236 is adjusted to operate on the currentimpressed by the source 232 onconductor 250, and the ringers at stations233, 234, and 235, are adjusted to be.' inoperative upon this characterof current; thus only a." single station of the selectedline is causedto be signalled. Upon removal by the wanted sub# scriber of his receiverfrom its hook a low resistance path throughhis transmitter circuit isclosed in the well known manner, and the current is thereby increasedsufficiently to cause the operation-of marginal relay 242, which uponoperating removes a short circuit fromi` around relay 243. Relay 243thereupon operates in turn and applies direct battery. 256 to its ownwinding, and to the conductor 244. The grounded battery 256 is the sainebattery as grounded battery 246, and the winding of relay 245 is thusshort circuited, and this relay is released.

Ringin current is thus disconnected from the cal ed line.

The operation of relay 243 closesalso'thev A following circuit, ground,right hand front contact of rela 243, upper right contact-of sequenceswitc spring 212 power magnet f of sequence switch 213, to groundedbattery,

and the sequence switch 213 is moved out of f position 6 and since theupper ri ht contact of sequence switch' 212 continues c osed in allpost1ons up to and including 15, thesequence switch 213 is driven intoposition 16.

A conversational circuit is now closed from the calling station 101 tothe called station 257 as follows: Grounded batand a circuit is closedfrom grounded uence switch spring'196, wiper 180, conac tor 203, uppercontact of sequence switch sprlng 210, left hand back contact andarmature of relay 245, wiper 224, conductor 254,

substation 257, conductor 255, wiper 223, right hand armature and hackcontact of relay 245, upper left contact of sequence switch spring 208,conductor 202, wlper 178,. sequence switch spring 195, upper rightwinding of repeating coil 13 to groun Upon the termination ofconversation the subscribers replace the receivers on the switch hooksand the above described conversational circuit is broken. Relay 14becomes deenergized and upon retracting its armature closes a circuitfrom ground, sequence swltch spring 15, armature and back contact ofrelay 14, power magnet of sequence switch 131 togrounded battery, formovin this sequence switch out of posit1on16. nder control of itscentering. spring 188 uence switch 131 moves into position 18. circuitis then closed from grounded sequence switch spring 167, driving magnet18 to grounded battery for energizing driving magnet `18, which uponattracting its armature presses the brush rod 176 against a constantlydriven roller 20. Brush rod 176,

wipers 178, 180 and 181, and brush-182, un-

der control of the roller 20, are moved in a downward direction. Whenthe brush 182 contacts with the conducting segment 16, a circuit isclosed from the grounded brush 182, the conducting segment 16, conductor17, upper right contact of sequence switch spring 170, power lmagnet ofthe sequence switch 131 to grounded battery, and the sequence switch 131is moved out of position 18 and into position 1. The upper contact ofsequence switch' spring 167 o ens the circuit of the driving magnet 18.he selector 116, and the sequence switch spring 131 are thus returned tonormal for use on a subsequent call.

When sequence switch 131 moves out of position 17 the circuit of windingof relay '205 is broken, and this relay upon retracting itsarmaturecloses a circuit from ground, armature and back contact of relay 205,upper left contact of sequence switch spring 2,12, power magnet ofsequence switch 213 to grounded battery, for moving sequence switch 213out of position 16 and into position 18. circuit is now closed fromground,

vsequence switch spring 258, driving magnet 260 to grounded batteryoperating thereby the magnet 260, which upon attracting its armatureforces the brush rod 221 into engagement with the down drive roller 261.The brush rod 221 and the wipers 223, 224, and 225, and the brush 214are moved in a downward direction. When the brush 214 contacts withconducting segment 215 a circuit is closed from grounded brush 214, theconducting segment 215, lower contact of sequence switch spring 216,power magnet of sequence switch 213 to grounded batter for moving thesequence switch 213 out of position 18 and into position 1. Sequenceswitch contact 258, thereby opens the circuit of down drive magnet 260.

By means of connecting board 237 the connections which exist in position6 of the sequence switch 213 can be readily changed at will, and thecharacter of ringing current applied to the called line in such positionof the sequence switch or in any other position may be varied at will,thus the character of ringing current to be employed can be changed whendesired without interfering with the numerical designation of the calledstation, or of any other station on the same line.

Station 235 may be signalled in the following manner: rlhe callingsubscriber 101 operates the register magnet 138 in the usual manner andthen causes the actuation of the register magnet 148 -two times, thusbringing the wiper 152 into contact with conductor 2. Upon actuation ofrelay 207 and the movement of sequence switch 213, through positions 2%and 3%, the number 2, 2', 1, 1', 0 and 0 relays are operated in themanner previously described, and the sequence switch 213 is brought torest in position 4. rlhe release of relay 207 thus closes a circuit byway of its left 7hand armature and back contact, sequence switch spring240, left hand armatureand back contact of relay 238, armature and backcontact of relay 242, left hand armature and back contact of relay 243,conductor 244, winding of relay 245, grounded battery 246, for operatingrelay 245. Left hand front contact of this relay is now connected by wayof the winding of relay 242, and the conductor'253 to conductor 262, andthe source 232, impresses upon called line the character of current forwhich ringer 235 is adjusted to respond, and to which the ringers 233,234 and 236 do not respond. rlihe wipers 223, 224, and 225, have beendriven to the same set of terminals as before the circuit of drivingmagnet 218, being closed by way of conducting segment 215, 228, 231, and232, as before. Thus it will be seen that the one set of terminals ismade use of for calling a plurality of stations on the same line, theauxilliary switch 213 being arranged to determine the character ofringing current which is to be impressed upon the selected set ofterminals.

In order that a clear understanding of the invention may be had, itshould be borne in mind that the selector 220 is not positioned 1ndirect response to the operation of the counting relays of the senderbuthunts a position determined by the setting of sequence switch 213which is variably positioned under the control of the sender. Thesequence switch is of light construction, and

y is very rapid in operation. It can therefore be fully positionedbefore the selector 220 has advanced into engagement with the first willbe brought into engagement with the seventh set of terminals, since itsdriving circuit will be successively completed by way ofcommutatorsegments 215, 228, 231, 291, 292, 293 and 232. However, whenthe selector reaches its seventh off normal position, its drivingcircuit is opened at the lower left hand contact of sequence switchspring 294 and theselector is brought to rest. 'In this case, since thesequence switch 213 is standing in position 3, cycle ringing currentwill be applied to the seventh set of terminals served by the selectorswitch.

In case sequence switch 213 is advanced in position 4 under control ofthe sender, the selector -220 will again engage its seventh set ofterminals, since its driving circuit will be successively completeduntil the seventh commutator segment isengaged, as is obvious from aninspection of the drawing. In this case, with the selector 220 in itsseventh position, and sequence switch 213 in position 4, 30 cycleringing current will be applied to the line terminating in the seventhset of terminals served by the selector.

In case sequence switch 213 is advanced in position 9 under the controlof the sender, the selector-220 will again be advanced.

into engagement with its seventh set of terminals, sincev as'before thedriving circuit of magnet 218 is completed through the va rious sequence"switch springs until .commu--K tator brush 214 engages segment 233. In

this case 45 cycle ringing current is applied to the lline terminatingin the seventh set of contacts by way of the lower left hand contact ofsequence switch spring 295. If sequence switch 213 is advanced intoposition 6 under the control of the sender the selectorswitch 220 isagain advanced into engagement with the terminals of the seventh line bymeans of circuits identical with those previously described. In thiscase the called line is supplied with 16 c cle ringing current by way ofthe lower rlght hand contact of sequence switch spring 252.

From the foregoing it is obvious that the selector switch 220 isadvanced into its seventh oi normal position whenever sequence switch213 is in any of the positions 3, 4, 6 or 9, and that ringing current ofdesired frequency is supplied in accordance with the particular settingof the sequence switch. This allows of terminal per line working.

1,4ea,seo

The cuttings of the sequence switch springs which control the movementof the selector switch have been disclosed so as to show only the methodin which four stations can be signaled selectively on the seventh line.This has been done to render more easily understood the method ofcontrol. It is obvious that by properly arranging the open and closedpositions of the control sequence switch springs that the princi le ofterminal per line ringing maybe app led to all the lines served by theselector.

I claim as my invention:

1. In a telephone exchange system a series of registers, a control relaytherefor, a calling substationV adapted to intermittently operate saidcontrol relay, a second station connected in shunt with said rst stationand comprising a condenser, and means operative upon the actuation ofsaid registers for discharging said condenserA through the winding ofsaid control relay.

2. In a telephone exchange comprising registers, a poly-station line, acondenser at each of the stations of said line, a calling device inseries with a control relay, said control relay causing the actuation ofsaid registers, and contacts operated by such registers for charging anddischarging said condensers through the winding of said control relay.

3. In a telephone exchange system a plurality of registers for recoring'the designation of a wanted line or station, automatic switchescontrolled by said registers, a

lpulse circuit for said registers, and means controlled-by saidregisters to reverse the current in s a1d pulse circuit.

4. In a telephone exchange system, a step by step register switch, apulse circuit for said register, and means controlled by said registerto reverse the direction of current iiow in said pulse circuit aftereach step of said register. Y

5. In a telephone exchange system, a plurality of step by step'registers for recording the designation of a wanted line or station, apulse circuit for said registers, and means controlled by said registersto reverse the direction of current flow in said pulse circuit aftereach step made by any one of said registers. Y

6. In a tele hone exchange sytsem, a plurality of calle polystatio'nines, a source o variously characterized calling currents, means at cachof the stations of said lines responsive to a single character ofcurrent, a switch operable by imulses for selecting a character ofcurrent an a` selector controlled by said switch for selecting a line.

c 7. In a telephone exchange system, a plurality of polystation lines, asource of variously characterimd ringing currents, means at each of thestations of said lines responsive to a single character of currents-a.

controlled by impulses for'selecting a character of current and aselector locally controlled by said switch for seizing a designatedyline.

8. ln a telephone exchange system, a plurality of stations connected toa single line, a source of variously characterized calling currents,means at each of said stations responsive to a single one of saidcurrents, a

10 switch operable by impulses for selecting a character of current, aselector controlled by said switch for selectin a line, and aninterconnection between sai switch and said selector such that apluralit of dierent settings of said switch result 1n a single settingof said selector switch.

In testimony whereof, l hereunto set my hand.,

GEORGE ALBEN E. LUNDELL.

